Fluoroscopy switching device

ABSTRACT

An apparatus and method is disclosed for preventing accidental overradiation of a patient in surgical procedures involving both fluoroscopy and endoscopy. Video outputs from the endoscope and fluoroscope are connected to a switching device. The endoscope generates a video signal having a first video format, and the fluoroscope generates a video signal having a second video format. The physician uses the switching device to select from between the endoscope video output and the fluoroscope video output for viewing on a video monitor which accepts a video signal of a predetermined video format. The switching device is operable to convert at least one of the endoscope video signal or the fluoroscope video signal to the predetermined video format which the monitor accepts. When the endoscope video output is selected for viewing, the switching device automatically deactivates the X-ray generator of the fluoroscope. When the switching device is actuated to select the fluoroscope video signal for viewing on the monitor, the switching device automatically reactivates the X-ray generator. In this manner, overradiation of the patient during periods when the fluoroscope is not being used is avoided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 371,382 filed on Jun. 26, 1989 now U.S. Pat. No. 4,993,404.

TECHNICAL FIELD

The present invention relates generally to apparatus for performingfluoroscopy and relates more specifically to a switching device forpreventing the accidental over-radiation of a patient and attendingmedical personnel during surgical procedures involving fluoroscopy andendoscopy.

BACKGROUND OF THE INVENTION

Endoscopes have long been widely used in medical procedures for directlyvisualizing the interior of a canal or body cavity. A recent improvementon the endoscope is the video endoscope, wherein fiber optics permit theendoscopic view to be displayed on a video monitor. Video endoscopyprovides a number of advantages over traditional endoscopy, includingpermitting more than one person at a time to observe the endoscopicview, permitting the physician to assume a more comfortable viewingangle, and permitting a videotape record to be made of the endoscopicprocedure.

Similarly, modern fluoroscopic technology presents advances overconventional radiography. In conventional radiography, X-rays areprojected through a patient onto a photographic film which, whichprocessed, will provide a fixed image of the patient's internalstructure. In fluoroscopy, the X-ray sensitive photographic film isreplaced by a fluorescent screen which, which subjected to X-radiation,produces a direct image of the object under investigation. Because theimage on the fluorescent screen is usually so faint that it is difficultto visualize with the unaided eye, the screen image is usuallyphotographed with a sensitive video camera. The video signal is thenprocessed to increase the brightness of the image, and the image isdisplayed on a video monitor for viewing by the physician. Fluoroscopyaffords two primary advantages over conventional radiography: first, theimage produced is direct, so there is no need for photographicprocessing; and second, the image is viewed in "real time", rather thanas a still photograph or series of still photographs, and can thus showmovement.

Surgical modalities are well known wherein video endoscopy is used inconjunction with dye-injection studies under fluoroscopy at varioustimes during the procedure. Examples of such procedures includeendoscopic management of biliary tract obstruction and endoscopicsphincterotomy. In these procedures, the physician uses an endoscope tomaneuver a catheter down the esophagus, through the stomach, and intoposition within either the bile duct or pancreatic duct. The endoscopicview is projected on a first video monitor. A quantity ofradiographically opaque dye is then injected through the catheterretrograde into the selected duct. Subsequently, the duct is viewedfluoroscopically on a second video monitor, and the X-rays illuminatethe dye to reveal obstructions in the biliary system. If the dye doesnot properly fill the duct, the catheter may have to be repositionedunder endoscopic supervision to permit further infusion of dye. Whenfurther dye has been infused, the physician again views the ductfluoroscopically. After the procedure has been completed within thefirst duct, the physician uses the endoscope to reposition the catheterwithin the other of the bile or pancreatic duct, and the dye injectionprocedure is repeated. The physician then switches back to thefluoroscopic view to visualize the second duct. Depending upon thesuccess of the initial dye injection into the second duct, the physicianmay again have to switch to the endoscope to reposition the catheterwithin the second duct, and then switch back to the fluoroscope to viewthe duct.

During steps when the physician is using the endoscope rather than thefluoroscope, fluoroscopy may inadvertently continue while thephysician's attention is occupied with the endoscopic procedure. Thepatient and attending medical personnel are thus exposed unnecessarilyto excessive dosages of X-rays during those periods when the physicianis not actually viewing the fluoroscope. Thus, there is a need toprovide a means for avoiding this accidental overexposure of the patientand attending medical personnel to X-rays during periods when thefluoroscope is not actually being used by the physician.

SUMMARY OF THE INVENTION

As will be seen, the present invention overcomes this and other problemsassociated with prior art modalities combining fluoroscopy and videoendoscopy. Stated generally, the apparatus of the present inventioncomprises an apparatus for preventing the accidental overradiation of apatient and attending medical personnel during surgical proceduresinvolving endoscopy and fluoroscopy. A switching device has a videooutput for connection to a video monitor. Video outputs from afluoroscope and an endoscope are both connected to the switching device.The switching device is operable to select the video output from thefluoroscope for output to the video monitor, or to deselect thefluoroscope view and select the video output from the endoscope fordisplay on the video monitor. Concurrently with deselection of thefluoroscopic video output, the switching device disables the X-raygenerator of the fluoroscope. Thus, by forcing the physician to selectone or the other of the two views for display on a single monitor, thepatient and attending medical personnel are not exposed to X-rays exceptduring those periods when the physician is actually viewing thefluoroscope on the video monitor.

Thus, it is an object of the present invention to provide an improvedapparatus for performing fluoroscopy.

It is a further object of the present invention to provide an apparatusfor minimizing exposure of a patient and attending medical personnel toX-rays during procedures involving fluoroscopy and anothervideo-assisted visualization technique.

It is another object of the present invention to provide a fluoroscopyapparatus wherein the X-ray generator is enabled only when the physicianperforming the procedure is actually viewing the fluoroscope.

Other objects, features, and advantages of the present invention willbecome apparent upon reading the following specification, when taken inconjunction with the drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a switching device according to thepresent invention for use with fluoroscopic and endoscopic medicalapparatus.

FIG. 2 is a schematic view of a switching device according to analternate embodiment of the present invention for use with fluoroscopicand endoscopic medical apparatus.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT

Referring now to the drawings, in which like numerals indicate likeelements throughout the several views, FIG. 1 discloses an apparatus 10for performing fluoroscopy in conjunction with endoscopy. The apparatusincludes a fluoroscope 12, a video endoscope system 14, and a switchingdevice 16 for directing a video output to an optional videocassetterecorder 17 and to a video monitor 18.

The fluoroscope 12 is of conventional design well known to those skilledin the art and will be described only briefly. The fluoroscope 12 of thedisclosed embodiment is the Philips Diagnost 92, though it will beappreciated that other fluoroscopes are easily adapted to the presentinvention. The fluoroscope 12 includes an X-ray generator 22, which is ahigh-voltage power supply operatively connected by means of a line 23 toan X-ray source 24. The X-ray source 24 propagates X-rays through thepatient 26 and onto an image intensifier 30. The image from the imageintensifier 30 is projected through optics 34 onto the lens of a videocamera 36, and the video output from the camera is sent by signal path38 to a control unit 40. The control unit 40 samples the video signalfrom the camera 36 and automatically controls the dose rate of the X-raygenerator 22 by sending a signal through a control line 42.

The video endoscope system 14 is also of conventional design and willthus be described only briefly. In the disclosed embodiment, the videoendoscope system 14 is the Olympus CV-1, though it will again beappreciated that other brands and models of video endoscope systems willbe easily adapted to the present invention. The system includes a videoendoscope 50 comprising a flexible tubing 52 approximately 12 mm indiameter and 120 cm in length. The tubing 52 internally houses a fiberoptic viewing tube, fiber optic light tubes for illuminating the fieldof view, and various guidewires for directing and manipulating theendoscope. An objective lens at the distal end of the fiber opticviewing tube projects an image of the field of view onto the lens of aminiature video camera mounted at the distal end of the endoscope 50.The video output from the endoscope 50 is then transmitted through aline 54 to a control unit 56 which processes image information from theendoscope.

Conventionally, the control unit 40 of the fluoroscope system 12 and thecontrol unit 56 of the endoscope system 14 would send their respectivevideo outputs to separate video monitors. However, according to thepresent invention, the video outputs from the fluoroscope and endoscopesystems 12, 14 are instead both routed to the switching device 16. Theswitching device 16 operates to select one of the two video signals toprovide a single video output to the videocassette recorder 17 andmonitor 18, as will now be described.

The switching device 16 is connected to a low-voltage power supply 60.The power supply provides 24 volts DC between a pair of terminals 61,62. In the disclosed embodiment, the 24 volt output is available at theX-ray table upon which the patient lies. The switching device 16comprises a foot switch 64 and a relay 66. The foot switch 64 of thedisclosed embodiment is a Gemswitch, catalog number GEM-36, manufacturedby Linemaster Switch Corporation, though the invention is by no meanslimited to any particular footswitch. The foot switch 64 is of the"momentary contact" variety, whereby stepping on the foot switch closesthe contacts and releasing the foot switch opens the contacts. One side64A of the foot switch 64 is connected by a conductor 68 to the positiveterminal 61 of the low voltage power supply 60. The other side 64B ofthe foot switch 64 is connected by a conductor 70 to one end 74A of acoil 74 of the relay 66. The other end 74B of the coil is connected by aconductor 75 to the return, or negative, terminal 62 of the low voltagepower supply 60. As an additional safety precaution, the case of thefoot switch 64 is connected by a grounding conductor 78 to a ground onthe low voltage power supply 60. With the circuit arranged as described,actuating the foot switch 64 will close the circuit across the terminals61, 62 of the power supply 60 and cause the relay 66 to be energized,and releasing the foot switch will open the circuit, de-energizing therelay.

The relay 66 of the disclosed embodiment of the switching device ismanufactured by AMF Potter & Brumfield, part number KUP 11015, but itwill be understood and this particular relay is disclosed only by way ofexample and is not critical to the invention. The relay 66 includesfirst and second switching elements 80 and 82. The video output of theendoscope 14 is connected via a signal path 83 to a normally closedcontact 80A of the first switching element 80, and the video output ofthe fluoroscope 12 is connected via a signal path 84 to a normally opencontact 80B of the first switching element. The pole 80C of the firstswitching element 80 is connected by a signal path 86 to the input ofthe videocassette recorder 17 and then, by signal path 88, to themonitor 18. In the disclosed embodiment, the signal paths 83, 84, 86,and 88 are shielded coaxial cables terminated in an appropriateconnector, such as a BNC connector. When the relay 66 is not energized,the video output of the endoscope 14 will be connected via the switchelement 80 to the videocassette recorder 17 and monitor 18. When therelay 66 is energized, the video output of the fluoroscope 12 will beconnected via the switch element 80 to the videocassette recorder 17 andmonitor 18.

The second switching element 82 of the relay 66 is a normally-openswitch. The second switch element 82 is connected by a pair of signalpaths 90, 92 to a pair of "enable" terminals 94, 96 on the X-raygenerator 22 of the fluoroscope 12. When the relay 66 is not energized,the switch section 82 will present an open circuit between the "enable"terminals 94, 96 of the X-ray generator 22, and the X-ray generator willbe disabled. However, when the relay 66 is energized, the switch section82 is closed, thereby connecting the "enable" terminals 94, 96 andenabling the X-ray generator.

Thus, when the foot switch 64 is released to de-energize the relay 66,the video signal from the endoscope 14 is connected via the first switchelement 80 to the videocassette recorder 17 and monitor 18, and thesecond switch element 82 is open to disable the X-ray generator 22. Whenthe foot switch 64 is actuated to close the switch and energize therelay 66, the video signal from the fluoroscope 12 is connected via thefirst switch element 80 to the videocassette recorder 17 and monitor 18,and the second switch element 82 is closed to enable the X-ray generator22. It will thus be appreciated that the switching device 16 serves adual purpose: it selects from between the video signals from thefluoroscope 12 and endoscope 14 for output to the monitor 18; and,responsive to deselection of the video signal from the fluoroscope, itdisables the X-ray generator 22 of the fluoroscope 12. As a consequence,the X-ray generator of the fluoroscope is enabled only when thephysician steps on the foot switch 64 to select the video signal fromthe fluoroscope for display on the video monitor 18.

It is not required that the relay 66 operate off of 24 volts. Rather, a24 volt relay was selected because of the availability of a 24 voltoutput at the X-ray table of the fluoroscope and because of the desireto use a low voltage for the switching relay from a safety perspective.It will also be appreciated that a reverse-biased diode or a varistor(not shown) may be connected across the coil 74 in a conventional mannerto reduce sparking in the foot switch 64 when the switch is released.

The use of the fluoroscopic switching device 10 will now be describedwith respect to a diagnostic procedure known as an endoscopic retrogradecholangiopancreatography ("ERCP"). The initial phase of this procedureis carried out under endoscopic supervision. To activate the videoswitching device 16 to display the endoscopic view on the monitor 18,the foot switch 64 is released to de-energize the relay 66. As aconsequence of de-energizing the relay, the first switching element 80is closed to connect the video signal from the endoscope to the monitor18 and videocassette recorder 17. As a further consequence ofde-energizing the relay 66, the second switching element 82 is open,thereby interrupting the circuit across the "enable" terminals 94, 96 atthe X-ray generator 22 and disabling the X-ray generator. Thus, whilethe endoscopic view is being displayed on the monitor 18, no X-radiationis being emitted.

With the endoscopic view thus displayed on the monitor, the physicianpasses the distal or viewing tip of the endoscope down the esophagus ofthe patient, through the stomach, and into the duodenum. Monitoring theendoscopic video image on the monitor, the physician locates the ampullaof Vater, the opening of the bile and pancreatic ducts. A polyethylenecatheter is then inserted under endoscopic guidance into the opening ofthe bile duct. Radiographically opaque dye is injected retrograde tofill the biliary system, including the gall bladder (if present) andbile ducts and up into the liver.

The physician then switches to the fluoroscopic view. To display thefluoroscopic view on the video monitor, the physician activates the footswitch 64, thereby closing the switch and energizing the relay 66.Energizing the relay 66 closes the first and second switching elements80, 82. Closing the second switching element 82 completes the circuitacross the "enable" terminals 94, 96 and actuates the X-ray generator22. X-rays are then propagated through the patient 26 and onto the imageintensifier 30, and the resulting image is projected on the lens of thevideo camera 36. The video signal is transmitted to the control unit 40of the fluoroscope, which samples the signal and automatically controlsthe dose rate of the X-ray generator 22 by sending a signal via signalpath 42. The video output from the fluoroscope is then transmittedthrough the coaxial cables 84 and across the closed first switchingelement 80 to the monitor 18.

The physician uses the fluoroscopic view to visualize the biliarysystem. If the dye has not satisfactorily filled the biliary system, thephysician may switch back to the endoscopic view to reposition thecatheter to infuse an additional quantity of dye into the biliarysystem. When the physician releases the foot switch 64, the relay isagain de-energized, opening the first switching element 80 to deselectthe fluoroscope view and causing the endoscope view to be displayed onthe video monitor. Concurrently, de-energizing the relay 66 opens thesecond switching element 82, opening the circuit across the "enable"terminals 94, 96 and disabling the X-ray generator 22. The risk ofaccidental exposure of the patient and attending medical personnel toX-rays while the physician is employing the endoscope is therebyeliminated.

When the catheter has been repositioned under endoscopic guidance andadditional radiographically opaque dye has been injected into thebiliary system, the physician actuates the switching device to switchback to fluoroscopy. Upon reselection of the fluoroscope, the switchingdevice re-enables the X-ray generator. The physician again visualizesthe biliary system on the video monitor to verify proper dyedistribution throughout the biliary system.

When the biliary system has been properly filled with radiographicallyopaque dye, dye must be infused into the pancreatic duct. The physicianreleases the foot switch 64 to deselect the fluoroscope view and todisplay the video image from the endoscope on the video monitor 18. Asthe fluoroscope view is deselected, the second switching element 82 isagain opened, interrupting the circuit across the "enable" terminals 94,96 and disabling the X-ray generator 22. The catheter is thenmanipulated under endoscopic guidance to position the end of thecatheter within the pancreatic duct. A quantity of radiographicallyopaque dye is then infused into the pancreatic duct, and the physicianactuates the switching device to display the fluoroscopic view on thevideo monitor. Stepping on the foot switch 64 to actuate the switchingdevice 16 to select the fluoroscopic view closes the second switchingelement 82 to enable the X-ray generator 22, thereby illuminating thedye in the pancreatic duct. If proper dye distribution throughout thepancreatic system is not achieved, the physician may have to switch backto the endoscope to reposition the catheter to infuse an additionalquantity of dye. Each time the physician selects the endoscopic view,thereby deselecting the fluoroscopic view, the X-ray generator 22 isdisabled to prevent exposure of the patient and attending medicalpersonnel while the physician is viewing the endoscope.

When the biliary and pancreatic systems have been properly infused withradiographically opaque dye, the physician can use the fluoroscopic viewto look for strictures or stenosis, dilation, or stones in the biliarysystem. In the pancreas, the physician looks for abnormalities orstrictures. A ragged stricture in the pancreas may indicate cancer. Ifdesired, a "hard copy" photograph of the fluoroscope may be takendirectly from the image intensifier 30 or from the video monitor 18.Also, a record of the entire procedure may be made using thevideocassette recorder 17. Since the video signal input into thevideocassette recorder is the same signal being input into the videomonitor, the resulting videocassette tape will show the serial sequencesof endoscopy and fluoroscopy, thereby providing not only an accuraterecord of the procedure but also a valuable teaching tool.

While the use of the switching device 16 has been illustrated withrespect to a diagnostic procedure, it will be appreciated that theinvention is equally well suited for therapeutic applications involvingfluoroscopy and video endoscopy. For example, the physician may maneuvera radiographically opaque balloon catheter into an obstructed duct underendoscopic guidance and then switch to fluoroscope to inflate theballoon and monitor its effects. As the physician uses the foot switch64 to select from between endoscopic and fluoroscopic views, theswitching device 16 enables or disables the X-ray generator 22 of thefluoroscope 12 to prevent irradiation of the patient and attendingmedical personnel during those periods when the physician has deselectedthe fluoroscopic view on the monitor.

While the present invention has been disclosed with respect to aswitching device for selecting from between a fluoroscopic view and anendoscopic view, it will be appreciated that the switching device mayalso be employed in conjunction with a fluoroscope and any othervideo-assisted visualization apparatus, with the same benefits ofreducing exposure to X-rays during those periods when the physician hasdeselected the fluoroscope. Also, it will be understood that theswitching device of the present invention may be adapted to select fromamong more than two video inputs, with the X-ray generator beingdisabled in response to selection of any video input other than thefluoroscope.

In the disclosed embodiment, energizing the single relay 66 causes bothof the switching elements 80, 82 to be actuated, concurrently selectingfrom between the video inputs and enabling or disabling of the X-raygenerator, as appropriate. While the disclosed embodiment depicts boththe selection from between the video inputs and the enabling ordisabling of the X-ray generator as being actuated in response to thesame mechanism, i.e. the relay 66, it will be appreciated that theactions need not necessarily be performed in direct response to the samemechanism. For example, actuation of the foot switch may directlyprecipitate only one of the two actions, with the other of the actionsbeing initiated responsive to performance of the first action. Further,while the relay 66 switches both switching elements 80, 82simultaneously, it is not critical to the invention that both switchingactions take place simultaneously. Thus, the present inventioncontemplates an arrangement which produces a slight delay between thetwo actions, and references herein to the two actions taking place"concurrently" are to be understood to means that the actions occur atsubstantially the same time.

While the system illustrated in FIG. 1 provides satisfactory resultswhen the fluoroscope 12 and the video endoscope system 14 have the samevideo format (number of scan lines per frame, number of frames persection, etc.), it will be appreciated that difficulties will arise ifthe fluoroscope 12 and the video endoscope system 14 generate videosignals which have different video formats. For example, while mostvideo endoscopes currently use a 525 line format, certain fluoroscopesemploy a 1024 line format for higher resolution. It will be appreciatedthat conventional video monitors cannot handle more than a single videoformat, and incompatibility problems therefore arise when the videoendoscope system and fluoroscope employ different video formats. Thisproblem is conveniently overcome by the use of a scan converter on thevideo output of one of the two systems (fluoroscope, endoscope) so thata single selected video format is always provided to the video monitor18.

FIG. 2 is a schematic view of a switching device 100 according to analternate embodiment of the present invention which is intended for usewhen the fluoroscope and endoscope employ different video formats. Inthe embodiment shown, the scan converter 102 is interposed between thefluoroscope 12 and video switching device 16 so that the output of thefluoroscope 12 is converted into the selected video format. The videooutput of control unit 40 is connected via signal path 84 to the inputof scan converter 100, and the output of scan converter 100 is connectedby signal path 84' to the switching device 16. Therefore, regardless ofwhether the fluoroscope or the endoscope is selected, a signal with theproper video format is provided to the video monitor 18.

Although the scan converter 102 is shown as being connected between thefluoroscope 12 and the switching unit 16, it will be appreciated that ascan converter 104 could instead by connected between the video outputof control unit 56 of the video endoscope system 14 and the videoswitching device 16. This configuration will be used if the monitor 18is designed to accept the video format of the fluoroscope 12 but isincompatible with the video format of the video endoscope system 14.Furthermore, it will be appreciated that the scan converters 102, 104may be used on the outputs of both the fluoroscope 12 and the videoendoscope system 14 to convert their video output signals into a thirdformat, if the video monitor 18 is designed to accept a format whichdoes not correspond to the format of either the fluoroscope 12 or thevideo endoscope system 14.

Finally, it will be understood that the preferred embodiment has beendisclosed by way of example, and that other modifications may occur tothose skilled in the art without departing from the scope and spirit ofthe appended claims.

What is claimed is:
 1. An apparatus for performing a surgical procedureinvolving endoscopy and fluoroscopy, comprising:a switching devicehaving a video output for connection to a video monitor which accepts avideo signal of a predetermined video format; an endoscope having avideo output connected to said switching device, said endoscopegenerating a video signal having a first video format; a fluoroscopehaving an X-ray generator, said fluoroscope further having a videooutput connected to said switching device, and said fluoroscopegenerating a video signal having a second video format; said switchingdevice being operable to select from between said video output from saidendoscope and said video output from said fluoroscope for output to saidvideo monitor; said switching device further being operable to convertthe video signal of at least one of said endoscope video output or saidfluoroscope video output to said predetermined format which said videomonitor accepts; and means operative concurrently with selection by saidswitching device of said video output from said endoscope fordeactivating said X-ray generator of said fluoroscope.
 2. The apparatusof claim 1, wherein said predetermined format of said video signal whichsaid video monitor accepts comprises said first video format, andwherein said switching device is operable to convert said fluoroscopevideo output to said first video format.
 3. The apparatus of claim 1,wherein said predetermined format of said video signal which said videomonitor accepts comprises said second video format, and wherein saidswitching device is operable to convert said endoscope video output tosaid second video format.
 4. The apparatus of claim 1, wherein saidpredetermined format of said video signal which said video monitoraccepts comprises a third video format, and wherein said switchingdevice is operable to convert said endoscope video output and saidfluoroscope video output to said third video format.
 5. An apparatus forperforming a surgical procedure involving endoscopy and fluoroscopy,comprising:a switching device having a video output for connection to avideo monitor which accepts a predetermined video format; an endoscopehaving a video output connected to said switching device, said endoscopevideo output having a first video format; a fluoroscope having an X-raygenerator, said fluoroscope further having a video output connected tosaid switching device, and said fluoroscope having a second videoformat; said switching device being operable to select from between saidvideo output from said endoscope and said video output from saidfluoroscope for output to said video monitor; said switching devicefurther being operable to convert the video format of at least one ofsaid endoscope video output or said fluoroscope video output to saidpredetermined format of said video monitor; and control meansoperatively associated with said X-ray generator and said switchingdevice and operative to select from between a first mode in which saidfluoroscope video output is selected by said switching device and saidX-ray generator is enabled, and a second mode in which said fluoroscopevideo output is not selected by said switching device and said X-raygenerator is disabled.
 6. The apparatus of claim 5, wherein saidpredetermined format which said video monitor accepts comprises saidfirst video format, and wherein said switching device is operable toconvert said fluoroscope video output to said first video format.
 7. Theapparatus of claim 5, wherein said predetermined format which said videomonitor accepts comprises said second video format, and wherein saidswitching device is operable to convert said endoscope video output tosaid second video format.
 8. The apparatus of claim 5, wherein saidpredetermined format which said video monitor accepts comprises a thirdvideo format, and wherein said switching device is operable to convertsaid endoscope video output and said fluoroscope video output to saidthird video format.
 9. A switching device for use with an endoscopewhich generates a video signal having a first video format, and afluoroscope which generates a video signal having a second video format,said fluoroscope having an X-ray generator, said switching devicecomprising:a video output for connection to a video monitor whichaccepts a video signal of a predetermined video format; a pair of videoinputs for receiving said video signals from said endoscope and saidfluoroscope, means for selecting from between said pair of video inputsfor output to said video monitor; means for converting at least one ofsaid video signals from said endoscope and said fluoroscope to saidpredetermined video format which said video monitor accepts; and meansoperative concurrently with selection of said video output from saidfluoroscope for output to said video monitor for deactivating said X-raygenerator of said fluoroscope.
 10. The apparatus of claim 9, whereinsaid predetermined format of said video signal which said video monitoraccepts comprises said first video format, and wherein said switchingdevice is operable to convert said fluoroscope video output to saidfirst video format.
 11. The apparatus of claim 9, wherein saidpredetermined format of said video signal which said video monitoraccepts comprises said second video format, and wherein said switchingdevice is operable to convert said endoscope video output to said secondvideo format.
 12. The apparatus of claim 9, wherein said predeterminedformat of said video signal which said video monitor accepts comprises athird video format, and wherein said switching device is operable toconvert said endoscope video output and said fluoroscope video output tosaid third video format.
 13. A switching device for use with a pair ofvideo devices generating video signals, one of said pair of videodevices generating a video signal having a first video format, and theother of said pair of video devices generating a video signal having asecond video format, said switching device comprising:a video output forconnection to a video monitor which accepts a video signal of apredetermined video format; a pair of video inputs for receiving videosignals from said pair of video devices; means for selecting frombetween said pair of video inputs for output to said video monitor;means for converting at least one of said video signals to saidpredetermined format which said monitor accepts; and means responsive toselection of the video input from one of said devices for disabling theother of said devices.
 14. A method for preventing the accidentaloverradiation of a patient during a surgical procedure involvingendoscopy and fluoroscopy, comprising the steps of:selecting frombetween an endoscope video signal from an endoscope, said endoscopevideo signal having a first video format, and a fluoroscope video signalfrom a fluoroscope having an X-ray generator, said fluoroscope videosignal having a second video format, for viewing on a single videomonitor which accepts a video signal having a predetermined videoformat; converting at least one of said endoscope signal and saidfluoroscope signal to said predetermined video format which said videomonitor accepts; and concurrently with selection of said video signalfrom said endoscope for viewing on said monitor, disabling said X-raygenerator of said fluoroscope.
 15. The apparatus of claim 14, whereinsaid predetermined format which said video monitor accepts comprisessaid first video format, and wherein said step of converting at leastone of said endoscope signal and said fluoroscope signal to saidpredetermined format of said video signal which said video monitoraccepts comprises converting said fluoroscope video output to said firstvideo format.
 16. The apparatus of claim 14, wherein said predeterminedformat which said video monitor accepts comprises said second videoformat, and wherein said step of converting at least one of saidendoscope signal and said fluoroscope signal to said predeterminedformat of said video signal which said video monitor accepts comprisesconverting said endoscope video output to said second video format. 17.The apparatus of claim 14, wherein said predetermined format which saidvideo monitor accepts comprises a third video format, and wherein saidstep of converting at least one of said endoscope signal and saidfluoroscope signal to said predetermined format of said video signalwhich said video monitor accepts comprises converting said endoscopevideo output and said fluoroscope video output to said third videoformat.